Thermal cut-out.



F. 1). REYNOLDS & J. SACHS.

THERMAL GUT-OUT; APPLIOATION FILED .TAN.7,'1908. RENEWED DEC. 12, 1908.

926,962, Patented July 6, 1909.

I T all whom it may concern:

UNITED STATES PATENT OFFICE.

FRANK D. REYNOLDS AND JOSEPH SACHS, 0F llAltlFOltl), (ONNlC YlIGUl, ASSIGF 'lRS TO THE SACHS COMPANY, OF HARTFORD, CfiNNl lff'llltlil, A. (10 RPORATION OF CONNECTICUT.

THE RMAL Application filed January 7, 1908, Serial No. 409,628.

Be it known that we, FRAN'h D. Rumours and JosEPn SAcns', citizensof the United States, residing at Hartford, county of Hartford, Connecticut, have invented certain new and useful Improvements in Tlurrmal (ut' 'Outs, of which the follmvin'g is a full, clear, and exact description.

Our im rovement relates to thermal cutouts and as for its object to produce a new and improved thermal cut-out which shall have superior advantages in construction and operation.

Heretofore the fusible members of safety fuses have been constructed of metallic strips having a rounded or rectangular sec tion. In order to prevent hanging of. the fusible strip or wire of inclosed fuses, when molten, it has been suggested that the strips be made of very thin metal for producing a maximum area of contact with the filling "and of radiating surface, and consequently rendering the dispersion of the molten metal easy and reducing the amount of metal required in the fuse strip for a certain carrying capacity. Such strips, aside from being fragile, would be of excessive widths when used with loose or granular fillings, neeessitating casings or tubes of undesirably large diameter and have, therefore, never been used commercially with such fillings. It has also been found that by subdividing the conductor into a number of parallel conductors connected in multi )le toQComr'non terminals at their ends, similar results would accrue, but such arrangements, aside from ossessing objections similar to those alrea rlystatcd, are in addition more or less complicated and possess inherent difficulties of manufacture and accurate operation. V

The primary object of our invention is to produce a fusible conductor for safety fuses,

whether they are exposed or inclosed, which will by its inherent construction reduce the amount of metaf required for a fuse of a cerv tain carrying capacity and yet eliminate the objection to the fuse strips of thin metal or thecomposite multi le conductors made u of a number of smal conductors in paralle To obtain this result we construct a single fusible conductor of. any desired carrying capacity of limited spread in any radial or diametric sectional direction, but yet of very large superficial surface or cross sectional outline. 'lhat is, the sectional outline or.

Specification of Letters Patent.

GUT-OUT.

Patented July 6, 1909.

Renewed December 12, 1908. Serial No. 467,221.

strip employed greater rigidity for a given amount of metal and is, therefore, easierto handle; it has a great radiating surface relatively to the metal contained in it. 'It

al 'ays has an elongated section of metal which is not in a horizontal plane-so that the attraction of gravitation will more readily cause the strip when fused to materially change its shape. l\:[oreover, when molten,

the parts will be acted upon more strongly by molecular attraction tending to draw them toward the center and thus assist in the disruption of the fuse. There will also be unequal strains in the parts of the strip when heated which will cause it to break down as desired. It canbcreadilycalibrated. When used in inclosed fuses it has, in addition to the advantages above mentioned, a large surface in contact with the filling and is widely distributed throu bout the filling,

and utilizes allportions 0 the filling, being substantially equidistant from the walls of the casing on all sides. While this improved construction may be used for either open or inclosed fuses, it is particularly desirable in the latter.

The following is a description of an embodiment of our invention, reference being had to the accompanying drawings, in whieh Figure 1 is a partial longitudinal section of an inclosed fuse embodying our invention; Fig. 2 is a cross section of the same on the line Fig. 1; Fig. 3 is a partial longitudinal section ofone end of an inclosed fuse cmbodying a modification of our invention; Fig. 4 is an enlarged section of the fuse strip of Fig. 3 on the line y of Fig. 5; Fig. 5 is a lan view of the strip in Fig. 3; Fig. 6 shows a hose 'strip similar to that shown in Fig. 1, with a modified calibration cut; Fig. 7' is an other modification of the fuse stri showinga sli htly different form and anot ier form of ca ibration cut ;Fig. 8 is a modification of the fuse strip of Fig. 1, showing twice as many projections.

Referring more particularly to the drawing, A is a fuse strip, preferably of zinc,which strip A on an enlarged in the preferred form is surrounded by a casing B and a loose filling C, as in ordinary inclosed fuses. The strip A is of such shape that its cross section presents a serrated out line, by which is meant an outline having alternate projections and indentations. The projections are shown as pointed, but obviously that is not necessary, since other forms of projections .niay be used; The strip A is connected to split terminals A of harder i-ietal of higher conductivity, such as copper, which are preferably soldered thereto, the strip being forced into the split end. In the forms shown,-these split conductors are con-.

nected to blade terminals 1) which enter through the caps E of the tubular case B, the

arts being secured by screws ll l and remforcing lates F While use strips constructed as thus far described operate successfully on overload and short circuit, it is desirable to provide at some point along the length of the strip (prel'- erably the center) a portion of attenuated or decreased section so as to further insure the rupture of the conductor at that point when molten, and thus eliminate any molten hanginggor the maintenance of electrical continuity while the metal is in a molten condition. Such attenuation may be provided by notching or perforating the strip with so-called calibration notches or holes, which further serve to accurately iii the blowing point of the strip, and in Fig. l is provided by the notches G. Fig. 6 shows a section oft-he fuse scale with a calibration hole G through its core. Fig. 7 shows a similar fuse strip having a cross section. in the form of a three-pointed holes G in the Wings. Fig. 8 shows a similar fuse strip having a cross section in the form of a six-pointed star with calibration notches G Fig.3 shows a strip in the form of a series of projections H on flat base 1, with calibration notches (1, connected to terminals A and blades l) and inclosed in a tuhular casing B with filling ll. ln all these terms the apexes of the pro]cctions are sul stantlally 1n the form of a circle, that being star with calibratioir the preferred construction, so as to have the strip equally distributed on all sides through the filling and equally distant from all parts of the tube or casing. in Fig. 3 is used, the extreme ends of the strip may be soldered or otherwise joined to the disks J at the ends of 'the terminals A These constructions admit of various modifications in form and proportions without departing fronr the spirit of our invention. l he'sectional area of the strip relatively to the sectional area of the casing is somewhat enlarged over what it would be in practice, this being necessary in order to clearly show the construction.

What We claim is:

1. A fuse strip of serrated cross-sectional outlines 2. A fuse strip of serrated cross-sectional outline, the spaces between the projections being substantially equal, the extremities of said projections lying substantially in acircle.

A fuse strip having angularly disposed, radially pro jecling and longitudinally extending flanges. 1

l. In a fuse, the combination of a fuse strip whose cross-scction has a serrated form, a casing inclosing said strip and a filling Within said casing.

5. ln emnbination, a fuse strip whose cross section has a serrated form, the extremities of the projections lying siibst antially in a circlc, a tube inelosing said strip and a filling within said tube.

(5. In combination, a fuse strip of serrated cross-sectional outline, an inclosing case, filling material in the case and around the strip When the form shown and terminals between which the strip is connect ed.

7.- A fuse strip of serrated cross-sectional outline having an attenuated cross-sectional area for a portion. of its length.

FRANK n. REYNOLDS. JOSEPH SACHS.

W i tncsses JAMES B. CLARK, Evnnn'r'r ll. MORSE. 

